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<h2 style="margin:0; background:#cedff2; font-size:120%; font-weight:bold; border:1px solid #a3b0bf; text-align:left; color:#000; padding:0.2em 0.4em;">Article of the Week - [[Process of Micturition - Anatomy & Physiology|Process of Micturition]]</h2>
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<h2 style="margin:0; background:#cedff2; font-size:120%; font-weight:bold; border:1px solid #a3b0bf; text-align:left; color:#000; padding:0.2em 0.4em;">Article of the Week - [[Rumination - Anatomy & Physiology|Rumination]]</h2>
 
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[[Image:sumlutshcemtri.jpg|right|thumb|350px|<small><center>A schematic overview of the lower urinary tract showing the nerves and muscles involved in micturition</center></small>]]
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[[Image:Diagram of ruminating contractions.jpg|thumb|right|150px|Diagram of ruminating contractions - Copyright RVC 2008]]
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'''Micturition is the normal process of the passive storage and active voiding of urine.'''
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Rumination is the process of digestion in the ruminant. It involves three simplified processes. the first is regurgitation which increases the surface area of food particles for digestion through further mechanical breakdown. The second is re-[[Mastication|mastication]] and the third reinsalivation. Reinsalivation increases the volume of saliva produced whilst chewing and allows minerals to be recycled.
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After entering the renal pelvis the modification of the urine is over in all domestic species other than the horse where mucin is added.  The urine passes along the [[Ureters - Anatomy & Physiology| ureters]] and enters the [[Urinary Bladder - Anatomy & Physiology|bladder]].  It is here that the urine is stored until it is to be voided.  Urine is not constantly excreted and it is only when there is a significant amount present in the bladder that the process of voiding occurs.  Both the [[Urinary Bladder - Anatomy & Physiology| Bladder]] and the [[Urethra - Anatomy & Physiology| Urethra]] have smooth muscle and thus receive autonomic influence with regard to their activity.  However the urethra also has an element of skeletal muscle giving the animal some degree of conscious control over the voiding of urine.
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===Sensory Innervation===
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==Process==
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The bladder has stretch receptors (alpha receptors in the neck and trigone, and beta receptors in the body) which detect fullness of the bladder. These impulse to the pelvic nerves and so to the sacral spinal cord. The urethra has afferents detecting flow, distension and pain that go via the pudendal nerve to the sacral cord.
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===Central Intregration===
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*Reflex initiated by mechanical stimlation of the receptors in the mucosa of the [[The Reticulum - Anatomy & Physiology|reticulum]], ruminoreticular fold and cardiac area of the [[The Rumen - Anatomy & Physiology|rumen]]
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The co-ordination of the urethralis and detrusor muscles from information recieved from the stretch receptors occurs in the '''pons'''. This micturition centre also branches to the thalamus, cerebellum and cerebral cortex. It is the cerebral cortex that is responsible for voluntary control of micturition.
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*Frequency of contractions depends on the animal's activity
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*E.g. Cattle fed on hay or straw have the most frequent contractions at 79-100 per hour during feeding, 55-76 per hour during rumination
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*E.g. Cattle that are resting (not feeding or ruminating) only have contractions 47-80 per hour
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*Discrete reticular contraction preceedes biphasic ruminal contraction (see [[The Rumen - Anatomy & Physiology#Ruminoreticular contraction|ruminoreticular contractions]])
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[[Process of Micturition - Anatomy & Physiology|Click here to read more]]
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*Rumination depends upon the coordination of the stomach movements with the thoracic wall and throat
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*Associated with inspiration against a closed glottis creating a negative pressure in the thorax allowing ingesta to be drawn into the [[Oesophagus - Anatomy & Physiology|oesophagus]]
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*Ingesta carried orally via an antiperistaltic wave
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*Controlled by rumination centres in the hypothalamus
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*Fibre increases stomach motility
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*Increase in [[Volatile Fatty Acids - Anatomy & Physioogy|volatile fatty acids]] decrease stomach motility
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[[Rumination - Anatomy & Physiology|Click here to read more]]
 
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